Incomplete `macro_rules` definition is deleted
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A-macros
C-bug
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- Rust
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Description
Given a macro_rules definition containing only a matcher without a body, rustfmt will delete the matcher text. e.g.
macro_rules! foo { (foo) }
Is converted to:
macro_rules! foo {}
This happens for any brace style, but only if they're the last token. e.g. the following works properly:
macro_rules! foo { (foo) => }
using rustfmt 1.7.0-stable (82e1608d 2023-12-21)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the issue with the provided incomplete macro_rules definition and run rustfmt using each brace style shown. Trace the macro_rules formatting path responsible for trailing matcher tokens, then verify that formatting preserves the matcher text while still handling the valid arrow form correctly.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100